marcandkimmie

Hello. My 86 Carrera with 248,000 miles (no engine rebuild other than valve guides) started making a loud scraping noise from the engine. It sounds more like it is coming from the left side of the engine.

What does a bad alternator bearing sound like?

What does a bad chain tensioer sound like?

Any ideas????

Thanks very much guys. This car is my wife's toy. I drive an 89 C4 daily...but really for fun the 86 is my weekend toy as well. It's been out of commission for 2 weeks and we miss driving the old girl. Any help or thoughts would really be appreciated.

- Marc

Peter Zimmermann

First thing - remove the alt/fan belt and start the car. Noise gone = alternator or housing problem. Noise still there = something more serious. "Normal" failed tensioner noise is usually similar to a sound one can imagine if suddenly someone put a bunch of small parts inside the engine and they're just flying around in there. Tensioner noise is usually loudest at idle...
Pete

MarkSchu

248K!!!! my god these things are unbelievable! Hope your problem is a small one. good luck

marcandkimmie

Thanks guys. Yes these cars are unbelievable. I just replaced the spark plugs, cap and rotor. The spark plugs looked quite good. No signs of trouble. The car runs very strong. A rebuild is in the future, but in the meantime I am enjoying how great the old car runs with that kind of mileage.

The valves are even pretty quiet...not as quiet as my 89 C4 (only 44,000 miles on the engine) but according to my mechanic a lot quieter than other lower mileage 911's.

I will try the fan belt. I hope it is not an internal issue. I can deal with the alternator!

scottb

No personal experience, but I've heard that a failed tensioner sounds like a chain being dragged over a metal trash can.

For the alternator bearing, take a look at the inside of the fan housing. If you see scrape marks, chances are the bearing in the alternator has failed.

If you have to pull the alternator, this would be a good time to polish the fan and housing!

Good luck!!